The present invention relates to an improvement of a ball retainer for holding balls while attached to a slider in a linear guide apparatus of such type that the slider is fitted over a guide rail so as to be movable relative to each other through the rolling of the balls.
A ball retainer for a conventional linear guide apparatus of this type is disclosed, for example, in U.S. Pat. No. 4,929,095 applied for by the present applicant.
As shown in FIG. 11, the linear guide apparatus to which the ball retainer 5 is attached is of such a type that ball rolling grooves 3 of a guide rail 1 are formed in rail side surfaces lb and rail corners lc. The ball retainer 5 is designed to hold balls B so as to prevent the balls from falling away, the balls being rollingly guided by the ball rolling grooves 3 formed at the guide rail corners lc and by ball rolling grooves 4 formed in inner surfaces of a slider 2 so as to confront the ball rolling grooves 3. Thus, the ball retainer 5 is interposed between an upper surface la of the guide rail 1 and an inner surface 2a of the slider 2, the inner surface 2a confronting the surface la on a recess of the slider 2 that is fitted over the guide rail 1.
As shown in FIG. 12, the ball retainer 5 is formed into a substantially rectangular frame as viewed from the top thereof. Stopper portions 6 are projected at both longitudinal ends of the ball retainer 5, each stopper portion 6 extending in the axial direction of the linear guide apparatus. In addition, ball holding grooves 7 are formed at both side edges of the ball retainer 5 as shown in FIG. 13, each ball holding groove 7 being arcuate in horizontal section. The ball retainer 5 is designed to be attached to end caps 2B that are fitted with both ends of the slider 2 by fitting the stopper portions 6 into insertion recesses (not shown) formed in the fitting surface of each end cap 2B.
As shown in FIG. 11, a retainer 5A for holding the balls B within the ball rolling groove 4 in the lower part of the slider 2 is wire-shaped and is designed to receive in a retainer escape groove 8 formed in the bottom of the ball rolling groove 3 in the side surface of the guide rail 1 when the slider 2 is assembled into the guide rail 1.
On the other hand, a dustproof seal is disclosed in U.S. Pat. No. 4,918,846 and Unexamined Japanese Utility Model Publication No. Hei. 1-82330, which have been applied for by the present applicant. That is, the dustproof seals are designed to block the ingress of foreign matters into the ball rolling grooves within the slider with seal portions (an inner seal) arranged within the slider. The seals are arranged at the same position in the recess of the slider as that at which the ball retainer is arranged, and is slidingly contacted with the upper surface of the guide rail.
However, the conventional ball retainer 5 proposed in U.S. Pat. No. 4,929,095 is a single-functional product that 4 is designed to hold the balls B within the ball rolling grooves on the upper part of the slider 2. Therefore, there is a problem in which the foreign matters cannot be prevented from entering into both ball rolling grooves 3, 4.
On the other hand, the conventional inner seal disclosed in U.S. Pat. No. 4,918,846 and Unexamined Japanese Utility Model Publication No. Hei. 1-82330 is also a single-functional product only having the sealing function, and therefore cannot hold the balls. As a result, when the inner seal is attached to the slider of a linear guide apparatus of such a type that the upper ball rolling grooves 3 are formed at the rail corners lc of the guide rail 1 as shown in FIG. 12, the balls cannot be held within the upper ball rolling grooves 4 on the side of the slider corresponding to the ball rolling grooves 3 formed at the rail corners. Thus, another problem is caused.